1. Field of the Invention
This invention relates to an image recording apparatus for effecting recording of images on a recording medium.
The recording medium covers, for example, thermosensitive paper, plain paper, a plastic sheet and the like. Also, the image recording apparatus covers, for example, a facsimile apparatus, a copying apparatus, a printer, etc. The images are, for example, numerals, characters, figures or patterns, and include transmitted images, images read from originals, output images of a computer, etc.
2. Related Background Art
Thermosensitive recording is very simple in its process and is suitable for making the apparatus compact and low in cost, and has recently been widely used in OA instruments such as facsimile apparatus and the like. On the other hand, thermal transfer recording is being popularized in the field of plain paper recording or color recording. With such situation as the background, there is seen the advent of a recording apparatus which can accomplish both thermosensitive recording and thermal transfer recording by the use of the same recording mechanism because of the similarity of these two recording processes.
However, in the conventional recording apparatus both for thermosensitive recording and thermal transfer recording, the same drive system is used in the two types of processes, and this has led to the necessity of setting the torque of the drive system in accordance with the process in which the load is greater.
FIG. 1 of the accompanying drawings shows an example of the apparatus according to the prior art. In FIG. 1, the reference numeral 6 designates a thermal head and the reference numeral 7 denotes a platen roller. In the case of thermosensitive recording, the reference numeral 8 designates thermosensitive paper, and in the case of thermal transfer recording, the reference numeral 8 denotes plain paper and the reference numeral 9 designates an ink sheet. In this example, the load torque during thermal transfer recording becomes greater by an amount corresponding to the ink sheet 9. Accordingly, the torque of the drive system is set to a value necessary for thermal transfer recording. On the other hand, during thermosensitive recording, the load decreases by an amount corresponding to the absence of the ink sheet 9 and therefore, the torque of the drive system becomes excessively great, and this has led to the possibility that the problems of damping, noise, etc, arise.